Transmission



Dec. 9, 1952 R. sMlRL TRANSMISSION Filed May 11, 1948 2 SHEETS-SHEET 1 ffl@ f 25 6g ze 52 55 63 l66A a2 695@ 71 73 if fnvenlor/ L nzirl R. L. SMIRL TRANSMISSION Dec. 9, 1952 Filed May 11, 1948 Patented Dec. 9, 1952 Richard L; Sinirl', La Grange, Ill., assignor to Borg-Warner Corporation, Chicago,- Il-L,a corporation of'Illinois- Application May 11, 1948; SerialNi-2'6338'9 Y l'Claim. 1l

'I-hisinvention relates t'ovariable speed trans'- mis'sionsand more particularly' toy sucht transmissions adapted for use inmotor vehicles, althoughsuitable for other purposes'.

An object ofthe inventio'nf is to'provid'e ai var-iable speedv transmission-affording multiple torque paths-- between power' and Ioad and inwhich. cou'- pling devices are selectively operable toeffect transitibnbetween the pathsa Another object of the invention istoprovide a transmission having' a novell arrang-ementy ofY friction coupling devices and gearing which'- p'rovide d'ual selective coupling means te' the@ power'- providing' element for the establishment-oi l'ow speed ratio and overspeedra-tiedrivingof! the loadfand'whichprov-ide direct drive by' compound coupling? ofI boththe devices;

Af further object-ofthe' invention is-toprovide an' improved`- transmission embodying planetary gearing adaptedto prov-ide' four forward variable speed ratio and reverse drives in coopera-tion with a plurality ofcouplingdevices-for connecting one or more elements of the' gea-ring to the powerproviding element-toeiect such drives.

Another object ef the invention is to'- provide a planetary' transmission embodyingvvv aplurality of clutches aording split'- torquepaths betweentlie planetary gearing and power-providing ele'- ment for selectively' transmitting drive*v tov oneV or more elements of the gearing, and? a plurality of brake devices for cen-trollingthe gearingto provide a plurality of forward Variable spe'ed'ratio and reverse drives ofthe load.

A furtherobject of thel inventionis toprovide a change-speedLmecha-nism andi transmission embodying-a pluralityI ofV duid-actuated clutches selectively operablel to-v connect the: power tothe mechanism to" thereby provideitwo lparallel torque paths therebetween; onev of saidi clutches beingspeed-res-pensive to connect the p'ower through the inechanisrnA tof theload foraiford-ing a smooth and gradual' drive ci?` the` load inthe transitionk from one speed ratio to' another.

AI further object of the'in'v'ention is' to' provide arr improved transmission employing planetary gearing adapted' to' provide al plurality of forward variablef speed raties including overdrive speed ratie'V an'd a pair efl friction clutches selectively engage'abl'e' tof transmit drivefromthe-'drive'shaft ofV the transmission: tof the gearing' inthel over'- driveand underdrive speediratioconditions thereof. f

novel. transmission utilizes two friction clutches-and: two sets-of. simple planetary gearing afford-ingfour forward variable speed ratios and' reversev driVethereb-y providingacompact arrangement which occupies less, space. than. that requiredl for' a standard 'gear transmission. 05er'- in'g'siin'il'ar' speed ratlos and lrevers'el dri've.- These andl other objects and advarta'ges` will appear as I' proceed withthe' description of the embodi- 2 ment.v of: tl'ie:i invention;Y whicin for" purposes of the present application;A I'h'ave illustrated'. in? the accompanying; drawings;r in" which;l

Fig.` I is'alongitudinal: sectienal`` view of the: transmissiony assembly embodying: my invention; andfv Fig;r 2 is ai section-L of.' the-structure: of' Eig. 1' taken-v alongf line; 2:-2 of. Fig. I,V showing the' actuating?v mechanism for oneof the brake devices; which is'. equivalent, to2 siiriilarmechanismy utilized to' actuateithei other brake/devices shownA inlFig. 1'.

Referring now toL thedrawings for' a; more. detailed`l description ofu the invention, IIlf' is the"V crankshaft of an engine which: also constitutes the drive or'inputshattof-A theftransmission.v The drive shaft Ill-has alradiallyf extending? flange connected-'tofa-Ilywheel IiI'by belts I2; I-2r- The engine: isprovided-` with: usualL crankshafthousing; (not shown) and to saidihousing is :secured a combinedclutchv andfv transmission. housing Iill;y The housing I'3- is provided with: a transverseendwall Hirotatalo'fly mounting the driven oroutput shaft I5- Intermediate the#v drive: sha-ttf I-Iln and driven shaft I=5 is a; shaft- IIG- supported` inl axial alignment with the shafts I-Ill and I5i byelements mounted'y on' af transverse wa/ll- I-'lf ot the housing as described hereinafterand-1 alsoby ball bearings- Ha.' disposed in the flywheel I IF and piloting the forward endv of the' shaft i6.

Secured: tothe'l iiywh'eel I-I- is ai multipleclutch assemblyY consisting of. two friction.'` clutcheslil and I9 capable of selective and conjointoperation, TheA clutchassembly comprises a driving member or pressure plate 20 which' issupported from and: driven4 by; the flywheel I I- throughY nexible' metallic straps' IE secured to the flywheel through the.- medium. of beltl andL nut assemblies; one of whichr is4 shown at 22';r each: assembly 2-2'. comprising; a bolt-extending1 through-the plate 20, bushings 23# and` 24- oni opposite sidesoi the'pla-te y 20,. straps 2-I,v and: oever?- plate- 25.;. thef'straps 2-I connecting; the platev 2i)l to: the flywheeland` restraining theplate-` against axial-movement; Disposedl o'nopposite sides ofthe plate 2Ilare the? driven clutch plates '2B` andl 2:1-, thei plate N5 ofthe clutch If havingitsl hub portionsplined to` the. intermediate: shaft- It. and: the. plate? 21' having; its huby portion splinedito anhollow sleeve 29r surrounding tlfiesh'af-t-` I6: and rotatable: relative thereto: Thefrictionf facings of' the' clutch plate 26 are' interposedY and are-` adapted. tofbeclamped between the'- platey 20- andi a pressure plate 30 to impart drivey from.- the-input-shattlll to. theshaft I 6, and similarly, the, friction facingsrof.' the y clutch plate 2JA are: disposed and may be-olarnped-v between. the plate 2U, and` pressure plate 31' to drive theI 'sleeve'- shaft 2`9`. The pressure plates 3U. and 3T are' carried ona plnrality'of bolt' and nut assemblies', one of which is shown at' 32', connected to the cover; plated 25:v and tliev flywheel, in-

such manner that they are held concentric and will rotate with the cover plate and flywheel but are free t-o be moved longitudinally by a spring on each bolt out of engagement with the clutch plates 2t and 2l and also to be moved into engagement with the clutch plates by the application of pressure to the drive plates 3Q and 3l, respectively, by fluid pressure actuating means now to be described.

The clutches I8 and le are adapted to be selectively engaged by fluid-pressure actuated mechanism and, for this purpose, the cover plate has bolted thereto a diaphragm plate 33 whose hub 34 is piloted on the sleeve 29 by roller bearings 35 and Se. The hub 35- extends through and is rotatably mounted on an annular collar Si extending within an opening in the central wall lll of the housing i3 and fixed to said wall. It will be apparent that the clutch member 2t, cover plate 25, diaphragm plate S3, and hub Si@ thus form an assembled unit secured at one end to the flywheel and rotatably mounted at its other end in the collar 3l. Disposed on opposite sides of the diaphragm plate 33 are annular flexible diaphragme 3S and 2Q having their outer peripheries clamped to the plate 33 by rivets id extending through the cover plate 25, diaphragm plate 33 and a clamping ring di, the inner peripheries of the diaphragm being clamped to the plate S3 by bolts 42 extending through an annular clamping -1 member 43 and threaded into the hub of the plate 33. The diaphragm is engaged with a piston fili laterally displaceable by the diaphragm to cause movement of the pressure plate 3l to clamp the driven clutch plate 2l of the clutch it between the plate 3l and driving plate 2% to effect rotation of the plate 2l and the sleeve shaft 29 by the drive plate 3l. rThe diaphragm 3@ has similarly associated therewith a piston i5 for actuating an engaged plate @t slidably connected to the bolts of the nut and bolt assemblies 32 and operative through its engagement with the nuts of said assemblies to impart movement to the assemblies and the pressure plate to effect engagement of the clutch I8. It will thus be seen that the clutches i8 and l can be conjointly or selectively engaged by actuation of the clutch pistons 44 and 45.

It may be noted that the diaphragm plate 33 and diaphragms 33 and 39 define uid chambers and 5I. For the purpose of conducting pressure fluid to the chamber 5i! to actuate the piston 44 to engage clutch lil, a passage 52 in the plate 33 communicates with the chamber 5e and a passage 54 in the rotating hub 3P of the diaphragm plate 33, the latter passage being connected with a source of fluid pressure, tc be described, by suitable ccntrol means. Pressure fluid can also be transmitted to the chamber 5l through a passageway (not shown) in the hub et of the plate 33 communicating with a source of uid pressure under the control of a valve or other control means. Actuation of the piston ifi and engagement of clutch le by pressure fluid in the chamber 5t is controlled by a centrifugalweight valve 55 disposed within a chamber 5e in the diaphragm plate 33 and adapted to be urged towards the axis of rotation of the plate it upon pressure fluid entering the chamber 543 and passing through a passage 5l communicating with the chamber 56, the valve 55 permitting the pressure fluid to ow there-around and into drain passage 58 in the plate 33 so that pressure will be unable to build up in the chamber 5G to effect actuation of the piston ed. However, pressure can be built up on the diaphragm 38 to actuate the piston it to engage clutch I8 when the engine speed is sufficient to effect movement of the valve radially outward of the axis of rotation of the diaphragm plate so that the valve offers resistance to the flow of the pressure fluid from the passage 5l to the drain passage 58. The clutch le is thus speed-responsive and will connect the motor to the load in a smooth and gradual manner during transition from one speed ratio to another, as will be later described.

For the purpose of providing fluid under pressure to actuate the pistons 44 and 45, the transmission is provided with two pumps generally indicated 59 and 69, the rst pump 59 being driven through the medium of the extended hub ed of the diaphragm plate 33, cover plate 25, drive plate 2d, and flywheel Il connected to the engine crankshaft It, this assembly being operatively connected together to effect operation of the pump whenever the engine is operating. The rear pump` 60 is driven by the output shaft le and can be utilized, in the event the engine will not start, to provide fluid pressure for operating the clutches when the driven shaft is rotated pushing or towing the vehicle.

The change speed mechanism of the transmission comprises a pair of planet gear sets generally indicated 52 and 63 adapted to be controlled by three fluid-pressure actuated brake devices G4, S5 and 66, for providing four forward speed ratios and reverse drive. The planet gear set d2 comprises a sun gear 61 splined to the adjacent end of the sleeve shaft 29, a ring gear 63, a series of planet pinions t@ meshing with the sun and ring gears 61 and 68 and rotatably mounted on stub shafts 1t, fixed to the planet carrier indicated at 'H and comprising a radially extending flange on the shaft I6. The planet gear set comprises a sun gear 12 rotatably mounted on the driven shaft l5; a ring gear 'd3 provided on drum 14, supporting the stub shafts lll and thereby forming part of the carrier 7l; and a series of planet pinions 'l5 rotatably mounted on stub shafts E6 xed to a carrier 11 coupled to the output shaft l5 and connected to the ring gear 63 of the gear set 62.

Referring to the brake devices 64, 55, and controlling the planetary gear sets 62 and EB to provide the various speed ratios and reverse drive, the brake device 64 comprises a drum titl coupled to the sun gear 61 of the gear set 62 and adapted to have applied thereto a brake band @l to prevent rotation of the sun gear which thus provides a reaction point for the establishment of overdrive speed ratio. The brake device 65 is adapted to hold stationary the carrier 'H of the gear set 62 and also the ring gear of the gear set t3 to provide reverse drive and comprises the drum 'M coupled to the ring gear 13 and carrier "H, and a brake band 82 engageable with the drum 14. The brake device 65 comprises a drum B4 splined to the sun gear 'l2 of the gear set t3 and adapted to be engaged by brake band 65 for holding the sun gear against rotation to provide a reaction point for the establishment of first and second or underdrive speed ratios.

To control the brake bands 8|, 32 and 85, the bands have associated therewith brake-applying devices, one of which is shown in Fig. 2. .Each of these devices is similar in structure and operative in an identical manner and, therefore. the device associated with the brake E5 comprising band 82 will only be described. As shown in Fig. 2, a cylinder 9| is formed integral with the housing`|3f and af' piston 912Y in the cylinder 9|; hasjits piston rod 92 extending outwardly of the cylinderand pivotally connected to theV extremity of a lever 94pivoted on apin 95v supported by'a boss onithe casingY I8 and adapted to actuate thel brake b'and82 into engagement with the drum 'I4 to prevent rotation thereof. For this purpose, the brake band surrounds the drum 14, and the anchor end 96 of the brake band 82 is provided with a notch receiving one end or a link or strut" with a notch IUI in the lever 94; The piston 92y is actuated by'iiuid pressure through the medium of a lever |02 which is suitably connected to a valve arrangement in the control device |03, xed

to thev casing I3, f or admitting uid pressure into the cylinder 9| and thereby the application of liuid pressure to thepiston 92. The piston 92'- will be moved by the pressure fluid against the pressure exerted Vthereon by a spring VIEM in the cylinderv 91| and seated against a cylindrical iiange of the cylinder defining the opening in the cylinder through which the piston rod 93 extends, andthe piston 92 will thereby effect actuation of the piston rod 93 to rotate the lever 94 about itsv pivot 95 in a counter-clockwise direction and move the thrust link` |09 to cause the band 82 to grip the braker drum' Trlv to prevent rotary movement thereof. To relieve the fluid pressure for disengagement of the brake, the lever |92 can beopera-ted to close the admission of pressurev a clockwise direction tor eiect the release of the brake band 82 from the' brake drum '14.

Describing the operation of the transmission, it will be assumed that the operator is in control of the fluid pressure directing systems for effecting actuation of the clutches IB and I9 and the brake devices 64, 65 and 66. At this time, the controls for operating the clutches and brake devices have notv been actuated by the operator and, therefore, a-neutral condition of the transmission will exist.

To obtain first or low speed ratio, fluid under pressure isV directed to the fluid chamber '59, and the engine is accelerated to effect radially outward movement ofthe valve body 55 by centrifugal force to close the passage l to build up fluid pressure in the chamber 5G to eect actuation of the diaphragm 35S and thereby pis'- ton M' to movethe pressure plate 3| to clamp the friction facings of the plate 2 between the pressure plates 2G andv 3i. With the clutch I9 engaged, the drive will be transmitted to the sleeveshaft 29; The brake device 65 is then engagedtoY holdthe sun gear 'I2 against rotation tol provide-a reactionY point for establishing low speed ratio; With the sungear 'I2 held stationaryydrive will loe-transmittedk from the sleeve shaft 29 and to-the-v sun gear 6'? fixed thereto, planet pinionsil, and ring geark EBS'to effect rotation of the drivenshaft I5'at low'speed.

To provide secon-d speed-ratio, the brake device 66 ismaintained in operative condition, the clutch. |'9'is released, andthe clutch I8 engaged. t will be apparent that, when pressure fluid is prevented from flowing to the chamber 59 by the operator, the fluid pressure in the chamber 5|] may be released to eiect disengagement of the clutch. I9 through th'etpassa'ges52' and 54; veven though the vcentrifugal weight valve 55 is'effective toV close the passage 57. At thisv time, pressure is directed to the chamber 5|, andthediaphragm 39 will` expand to force'the piston 45 against thev plate 46 which will beiV urged to the right to engagethe pressure plate 30 with the friction clutch facingsof theclutch plate 26 ofthe clutch I8 to clamp' these facings between the pressure plate 30Y and 20 to' impart drive from the' crankshaft I9 to the shaft' It'.v With drive being transmitted from the shaft II)- to the. shaft I6, the carrier 'I'I isl rotated. Asfthe brake 561s operative, the sun gear 12, will be eiective to establish areaction causing thel ring'gearV 68 and driven shaft Ilv tov rotatef'orwardly in second speed' ratio.

Third speed ratio ordirect' drive is provided by releasing'th'e brake device' 66 and engaging the clutch I 9 sov thatboth of the clutches I8' and I9' will be engaged. InV this' condition of the' transmission, it will be'apparent that the shafts 2'9an'd I6 will rotate' in unison and `effect rotation of the sun gear''l'and carrier 'II of the planet gear set 62 so that. the gear'set 2'will be locked up and, accordingly', the ring gear'v |53 thereof and the'driven. shaftl I5 will be driven atthe samje speedl as that of the drive shaft I9.

To obtain fourth speed ratio or overdrive, clutch I9' is disengaged, clutch I8 remains engaged, and brake' device 64 is engaged to hold the' drum 80 andthereby sun gearv 61 ofthe-gear set BZ'statiOnary to provide a reaction point for conditioning the planetary'gear' set 62 to eiect drive `of' the drivenl shaft I5 at a speedy greater than that'of thedrive shaft |:`orin` an overdrive' speed' ratio. lVithl thedrive shaft |91 clutch' I8',

shaft I6, andL the'reby'the' carrier 'II of the gear set GZ'bein'g rotated" at the'sarne speed, it. will be apparent that the stationary sun' 'gear' 6T is'efe'ctiveto cause-therring gear 68"arid therebythe driven shaft It?` to' be rotated at` an overdrive' speed;

I'oobtain'reverse'drive;` the. clutch' |9"is' engaged /and the brakedevice 65 is alsotoperated" to hold' the'drum: liarid planet c'arrier"|"|` against rotation; DriveY will be transmitted from the drive shaft Ill through the engaged clutch |`9 v to theisleevemsliaft 29 connected to the sun gear 61 and; asthe' planet carrier I'Iv is stationary, forward rotation' of. the su-n' gear .67, will' cause the' planet pinion 69` to rotateY the ring gear 68v and. thereby the. drivenshaf-t I5 inY a direction opposite. to that ot'th'edirection of-rotation of thedrive shaft IIJ'.A

It` Will bev apparent from the-"foregoing description ofl the transmissionthatthis transmissionV is --extremelfy exible-ineiecting changesof speed ratioinasmuch asthe transition'- successively frominitialor low speed-ratio to second, third,

and: fourth speedV ratios iseffected by merely engagingA orrele'asingr one ofl the clutchesi or" one of the brake bands as will be apparentY froman inspection.: of' the following: actuation pattern of their clutch: and Y: brakeele'rents designated and` inl To initiate movement of the vehicle, Clutch i9 and brake band 85 are engaged. Thereafter, to establish second speed ratio, it is only necessary to engage the clutch i9 while disengaging the clutch I9. Third speed ratio or direct drive is then easily obtained by releasing the brake band 95 while engaging the clutch i9. To change from third speed ratio to fourth speed ratio or overdrive, the clutch i9 is disengaged and bralre band 3l is engaged. It will thus be apparent that a simple ratio changing schedule is provided requiring operation of only one of the clutches or one of the brake devi es to eiect the transition from one speed ratio to the next succeeding speed ratio. Furthermore, the clutches brake devices, controlling the transmission, permit downshifting of the transmission in a simple and readBr manner from second, third or fourth speed to the next lower speed ratio. Referring to the above noted shift pattern, it will be noted that by simply releasing the brake band El and engaging the brake band 95 the transmission may be downshifted from overdrive to second speed, and the downshift from third speed ratio or direct drive to second speed ratio is quickly effected by dis engaging clutch S9 and engaging brake band 95. It will thus be seen have provided a novel and improved transmission capable of meeting any of the driving conditions which the driver of the automotive vehicle may encounter and where it is required to eifect transition from one of the speed ratios to another speed ratio according to the demand of the operator.

One very important feature resides in the provision of a speed-responsive fluid-actuated clutch in the establishment of rst speed ratio and effecting transfer from second speed ratio to third speed ratio so that smooth and gradual engagement of these speed ratios will be realized.

Another important feature is that the four variable forward speed ratios are successively completed by friction clutch and brake devices which allow the smooth shifting from one speed ratio to another, the successively operated devices overlapping in such manner as to yield continuous torque during ratio change interval which prevents torque shock.

t will be noted that the transmission, as a whole, has a minimum number of control elements, namely, only two friction clutches and three friction brakes being utilized for providing four forward speed ratios. By the utilization of two friction clutches to provide divided torque paths between the power-providing element I and the compound epicyclic gearing, the clutches may be compressed into a relatively small space and this feature, together with the fact that the gearing is composed of only two groups of simple planetary units, is of considerable importance in providing a compact transmission having dimensions which occupy less space than that required for a standard transmission affording similar speed ratios.

I wish it to be understood that my invention is not to be limited to the specific constructions and arrangement shown and described, except only insofar as the claim may be so limited, as it will be apparent to those skilled in the art that changes may be made without departing from the principles of the invention.

What is claimed is:

1n a transmission, the combination of a drive shaft, a driven shaft, a compound planetary gear unit comprising a first planet gear set and a second planet gear set, each of said sets comprising a sun gear, a ring gear, a planet gear in mesh with the sun and ring gears and a planet gear carrier, the ring gear of said first set and the carrier of said second set being connected with said driven shaft for driving the shaft, the carrier of said first set being connected with the ring gear of said second set, means for providing a direct drive between said shafts and including a first friction clutch for connecting the sun gear of said first set with said drive shaft and a second friction clutch for connecting the carrier of said first set and the ring gear of said second set with said drive shaft which clutches when both are engaged lock the elements of said gear unit together so that they all rotate as a unit and provide the direct drive, a fluid pressure actuated piston for engaging each of said clutches, centrifugal Valve means responsive to the speed of rotation of said drive shaft and varying the pressure applied to the piston for said first clutch according to drive shaft speed, fluid passage means for relieving the fluid pressure applied to the piston for said rst clutch for selectively releasing and engaging the same when the centrifugal valve means are operative, means for providing low and intermediate reduced speed drives from said drive shaft to said driven shaft through said gear unit and including a friction brake for the sungear of said second gear set which when it and said first clutch are engaged completes said low speed drive and when it and said second clutch are engaged with said rst clutch disengaged completes said interm-odiate .sp-eed drive, means for providing an overdrive from said drive shaft to said driven shaft through said gear unit and including a friction brake for thesun gear of said rst gear set which when it and said second clutch are engaged with said rst clutch disengaged completes the overdrive, means for providing a reverse drive from said drive shaft to said driven shaft through said gear unit and comprising a friction brake for the carrier of said first set and the ring gear of second set which when it and said first clutch are engaged completes the reverse drive, and a fluid pressure responsive means including a fluid actuated piston for engaging each of said brakes.

RICHARD L. SMIRL.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,609,732 Small et al Dec. 7, 1926 1,991,124 Sharpe Feb. 12, 1935 2,046,428 Riley July 7, 1936 2,143,321 Kegresse Jan. 10, 1939 2,163,202 Kegresse June 20, 1939 2,231,411 Lawrence Feb. 11, 1941 2,291,241 Lawrence July 28, 1942 2,319,549 Lawrence May 18, 1943 2,328,090 Nutt et al Aug. 31, 1943 2,328,092 Nutt et al Aug, 31, 1943 2,395,459 Carnagua Feb. 26, 1946 2,418,378 Voytech Apr. 1, 1947 2,440,589 Kegresse Apr. 27, 1948 FOREIGN PATENTS Number Country Date 469,881 Great Britain Aug. 3, 1937 

